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Origin of impurities formed in a polyurethane production chain. Part 2 / June Callison in Industrial & engineering chemistry research, Vol. 51 N° 34 (Août 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 34 (Août 2012) . - pp. 11021-11030 Titre : Origin of impurities formed in a polyurethane production chain. Part 2 : A route to the formation of colored impurities Type de document : texte imprimé Auteurs : June Callison, Auteur ; Franziska Betzler, Auteur ; Kimberly de Cuba, Auteur Année de publication : 2012 Article en page(s) : pp. 11021-11030 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Color  Production  Impurity Résumé : The quality of methylene diphenyl diisocyanate (MDI) products, which are valuable feedstocks in the industrial manufacture of polyurethanes, can be compromised by the presence of color, presumed to arise from trace impurities. One undesired branch in the synthesis chain originates with phosgenation of diaryl ureas, formed from reactions between aryl isocyanates and polyamine precursors. Subsequent key steps include, (i) breakdown of the primary compounds, substituted chloroformamidine-N-carbonyl chlorides (CCC), to give aryl isocyanide dichlorides, ArNCCl2, (ii) an apparent equilibrium connecting CCC with aryl carbodiimides, and (iii) the thermolysis of ArNCCl2 in the presence of MDI. Color formation is associated directly with the last process; it involves several events, including HCl elimination from reaction of ArNCCl2 and MDI, formation of carbon-centered radicals, and a contribution from oxidation at the methylene bridge. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26299424 [article] Origin of impurities formed in a polyurethane production chain. Part 2 : A route to the formation of colored impurities [texte imprimé] / June Callison, Auteur ; Franziska Betzler, Auteur ; Kimberly de Cuba, Auteur . - 2012 . - pp. 11021-11030. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 34 (Août 2012) . - pp. 11021-11030 Mots-clés : Color  Production  Impurity Résumé : The quality of methylene diphenyl diisocyanate (MDI) products, which are valuable feedstocks in the industrial manufacture of polyurethanes, can be compromised by the presence of color, presumed to arise from trace impurities. One undesired branch in the synthesis chain originates with phosgenation of diaryl ureas, formed from reactions between aryl isocyanates and polyamine precursors. Subsequent key steps include, (i) breakdown of the primary compounds, substituted chloroformamidine-N-carbonyl chlorides (CCC), to give aryl isocyanide dichlorides, ArNCCl2, (ii) an apparent equilibrium connecting CCC with aryl carbodiimides, and (iii) the thermolysis of ArNCCl2 in the presence of MDI. Color formation is associated directly with the last process; it involves several events, including HCl elimination from reaction of ArNCCl2 and MDI, formation of carbon-centered radicals, and a contribution from oxidation at the methylene bridge. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26299424